A conventional pharmaceutical injection device comprises a main body case having an injection needle insertion and retraction opening, a pharmaceutical syringe mounting portion provided inside this main body case, a pharmaceutical syringe mounted to the pharmaceutical syringe mounting portion, a piston provided movably with respect to the pharmaceutical syringe, a drive mechanism that drives this piston, and a controller that is electrically connected to the drive mechanism.
Also, the pharmaceutical syringe has a cylinder and a push-in gasket that is provided on the rear end side inside the cylinder.
That is, the pharmaceutical can be injected through an injection needle into a body or the like by pressing the push-in gasket with the piston (see Patent Literature 1: Japanese Laid-Open Patent Application 2009-279438, for example).